// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_BASE_DRAGDROP_DRAG_SOURCE_WIN_H_
#define UI_BASE_DRAGDROP_DRAG_SOURCE_WIN_H_

#include <objidl.h>
#include <wrl/implements.h>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "ui/base/ui_base_export.h"

namespace ui {

class OSExchangeData;

// A base IDropSource implementation. Handles notifications sent by an active
// drag-drop operation as the user mouses over other drop targets on their
// system. This object tells Windows whether or not the drag should continue,
// and supplies the appropriate cursors.
class UI_BASE_EXPORT DragSourceWin
    : public Microsoft::WRL::RuntimeClass<
          Microsoft::WRL::RuntimeClassFlags<Microsoft::WRL::ClassicCom>,
          IDropSource> {
public:
    DragSourceWin();
    ~DragSourceWin() override { }

    // Stop the drag operation at the next chance we get.  This doesn't
    // synchronously stop the drag (since Windows is controlling that),
    // but lets us tell Windows to cancel the drag the next chance we get.
    void CancelDrag()
    {
        cancel_drag_ = true;
    }

    // IDropSource implementation:
    HRESULT __stdcall QueryContinueDrag(BOOL escape_pressed,
        DWORD key_state) override;
    HRESULT __stdcall GiveFeedback(DWORD effect) override;

    // Used to set the active data object for the current drag operation. The
    // caller must ensure that |data| is not destroyed before the nested drag loop
    // terminates.
    void set_data(const OSExchangeData* data) { data_ = data; }

protected:
    virtual void OnDragSourceCancel() { }
    virtual void OnDragSourceDrop();
    virtual void OnDragSourceMove() { }

private:
    // Set to true if we want to cancel the drag operation.
    bool cancel_drag_;

    const OSExchangeData* data_;

    DISALLOW_COPY_AND_ASSIGN(DragSourceWin);
};

} // namespace ui

#endif // UI_BASE_DRAGDROP_DRAG_SOURCE_WIN_H_
